Camera devices which use cover glass or a lens to protect an optical chain from dust or other debris entering the optical chain may suffer from reflections when the optical chain includes a mirror.
Many times stray light at off angles may enter via the light entry opening of the camera. Stray light entering the light path of the optical chain maybe reflected off the mirror up towards the cover glass or lens from where it reflects back again down towards the mirror. Many times such stray light hitting the mirror for a second time after being reflected by the cover glass may, depending on the configuration of the optical chain and arrangement of elements, proceed towards the image sensor of an optical chain and thus form unwanted image.
While such reflections may not be significant for most objects, when a light source itself is the source of the stray light, it maybe of sufficient intensity that the reflected stray light maybe noticeable in the captured image. This can result in what appears to be a strange image of, for example, a light fixture appearing in an image of an intended object in the field of view when the light source was not in the original intended field of view. This effect is sometimes referred to as “ghosting” since the light source which had some of its rays unintentionally reflected on to the image sensor of an optical chain appears as a faint image, e.g., as a “ghost image” at a location in the captured scene where the light fixture is not actually located.
Given that such ghosting effect is undesirable and for objects outside an intended field of view to appear as “ghosts” in a captured image degrades the desirability of the captured image, there is a need for methods, apparatus and/or camera element configurations which allow for a mirror or other light redirection element to be used without causing significant unintentional ghosting of objects, such as light sources, in an image.